The present invention relates to a semiconductor device and its manufacturing method. More particularly, the present invention relates to a technique effectively applied to a manufacturing method of a so-called CSP (Chip Scale Package) type semiconductor device, in which a size of an encapsulation is close to that of a semiconductor device chip.
With the increasing demand for the size and thickness reduction of the semiconductor device (semiconductor integrated circuit device), a wiring film substrate such as a film made of an insulating resin layer has been used. The use of such a film substrate makes it possible to achieve the reduction in thickness of the semiconductor device.
A manufacturing method of the CSP type semiconductor device having solder bumps in which a wiring film substrate (wiring film) is used is disclosed in the gazette of Japanese Patent Application Laid-Open No. 11-102944.
In this document, the manufacturing method of a semiconductor device is described, which comprises the steps of: (1) temporarily fixing a wiring film on a support plate having an attachable/detachable punching return portion; (2) fixing a semiconductor chip, connecting bonding wires, and forming a resin encapsulation layer; (3) removing the punching return portion and forming solder bumps in a lattice pattern on a rear surface of the wiring film; and (4) dividing the wiring film by cutting the connection portions at the four corners of the cutting lines previously provided along the edges of the resin encapsulation layer. In this manufacturing method of a semiconductor device, the edges of the wiring film are protruded from the outer rim of the resin encapsulation layer serving as an encapsulation.
For the achievement of the reduction in thickness of the semiconductor device, the inventors of the present invention had been considering a semiconductor device with a thickness of about 0.5 mm or smaller in which a semiconductor chip with a thickness of about 100 xcexcm or smaller is incorporated. Then, the inventors of the present invention considered the manufacturing method of a semiconductor device, using a film strip (film wiring strip) and capable of manufacturing a large number of semiconductor devices at once.
However, since the film substrate does not have sufficient rigidity, it is difficult to transfer it on the production line. Thus, the present invention has been made through the consideration of the application of the block molding method in which the film substrate is supported by a support frame to improve the workability and a large number of devices can be manufactured at once.
An object of the present invention is to provide a technique for manufacturing a thin semiconductor device.
Another object of the present invention is to provide a manufacturing method of a thin semiconductor device capable of reducing the manufacturing cost.
Another object of the present invention is to provide a technique capable of manufacturing a thin and small semiconductor device at low cost.
The above and other objects and novel characteristics of the present invention will be apparent from the description and the accompanying drawings of this specification.
The typical ones of the inventions disclosed in this application will be briefly described as follows.
(1) An aspect of the present invention is a semiconductor device, which comprises:
a wiring substrate with a main surface, a rear surface opposite to the main surface, and side surfaces between the main surface and the rear surface;
a semiconductor chip fixed to the main surface of the wiring substrate;
connecting means for electrically connecting terminals of the semiconductor chip to wirings on the main surface of the wiring substrate;
an encapsulation made of insulating resin which covers the semiconductor chip and the connecting means; and
conductors penetrating through the wiring substrate and having one ends connected to the wirings on the main surface of the wiring substrate and the other ends protruding to the rear surface of the wiring substrate to form external terminals,
wherein the semiconductor chip is thicker than the wiring substrate, and the wiring substrate is thicker than the external terminal.
(2) Another aspect of the present invention is a method of manufacturing a semiconductor device, which comprises the steps of:
preparing a wiring mother strip having a peripheral portion supported on a support frame and semiconductor device forming areas arranged and formed vertically and horizontally on the main surface thereof;
fixing a semiconductor chip to each of the semiconductor device forming areas of the wiring mother strip;
connecting the terminals of the semiconductor chip to the wirings on the main surface of the wiring mother strip via connecting means;
forming an insulating resin layer on the main surface of the wiring mother strip so as to cover the semiconductor chips and the connecting means;
fixing the wiring mother strip to a support portion so that the rear surface of the wiring mother strip opposite to the main surface faces upward;
cutting the wiring mother strip and the insulating resin layer along the boundaries between the semiconductor device forming areas by a blade; and
separating each of the semiconductor devices from the support portion.
(3) Another aspect of the present invention is a method of manufacturing a semiconductor device, which comprises the steps of:
preparing a semiconductor wafer having semiconductor chip areas arranged and formed vertically and horizontally on the main surface thereof;
preparing a wiring mother strip having a peripheral portion supported on a support frame and semiconductor device forming areas arranged and formed vertically and horizontally on the main surface thereof;
forming a plurality of semiconductor chips by cutting the semiconductor wafer vertically and horizontally;
fixing the semiconductor chip to each of the semiconductor device forming areas of the wiring mother strip;
connecting the terminals of the semiconductor chip to the wirings on the main surface of the wiring mother strip via connecting means;
forming an insulating resin layer on the main surface of the wiring mother strip so as to cover the semiconductor chips and the connecting means;
fixing the wiring mother strip to a support portion so that the rear surface of the wiring mother strip opposite to the main surface faces upward;
cutting the wiring mother strip and the insulating resin layer along the boundaries between the semiconductor device forming areas by a blade; and
separating each of the semiconductor devices from the support portion.
(4) According to the above (3), the step of forming a plurality of semiconductor chips by cutting the semiconductor wafer vertically and horizontally includes the steps of: forming adhesive on the rear surface of the semiconductor chip and then adhering the side of the semiconductor wafer with adhesive to a dicing tape; and cutting the semiconductor wafer along the boundaries between the semiconductor chip areas on the semiconductor wafer by a dicing blade.
(5) According to the above (3), the step of fixing the semiconductor chip to each of the semiconductor device forming areas of the wiring mother strip includes the steps of: picking up the plurality of semiconductor chips in (4) adhered on the dicing tape one by one from the dicing tape, with the adhesive being applied on the rear surface of the semiconductor chip; and fixing the picked-up semiconductor chips to the semiconductor device forming areas of the wiring mother strip via the adhesive on the rear surface thereof.
In the semiconductor device, the thickness of the wiring mother strip is about 70 xcexcm or smaller, the thickness of the semiconductor wafer is about 100 xcexcm or smaller, the thickness of the external terminal is about 30 xcexcm or smaller, and the thickness of a part of the insulating resin layer on the wiring mother strip is about 400 xcexcm or smaller. Therefore, the thickness of the semiconductor device is about 0.5 mm or smaller.
According to the semiconductor device and its manufacturing method, semiconductor chips with a thickness of about 100 xcexcm or smaller are fixed to the main surface of the thin film like wiring mother strip with a thickness of about 70 xcexcm or smaller, the wire bonding therebetween is performed, the semiconductor chips and the bonding wires are covered with an insulating resin layer, bump electrodes with a thickness of about 30 xcexcm are formed on the rear surface of the film like wiring mother strip, and then, the film like wiring mother strip and the insulating resin layer are cut lengthwise and crosswise. In this manner, the thin semiconductor devices with a thickness of about 0.5 mm or smaller can be manufactured.
In addition, since the film like wiring mother strip is cut together with the insulating resin layer after the formation of the insulating resin layer, it is possible to manufacture a large number of semiconductor devices at once and consequently to reduce the manufacturing cost of the semiconductor device.
Furthermore, since the semiconductor devices are manufactured by cutting the film like wiring mother strip together with the insulating resin layer lengthwise and crosswise, the side surfaces of the encapsulation in the manufactured semiconductor device formed by cutting the insulating resin layer are vertical to the film like wiring mother strip, and also, it is unnecessary to form slant faces in consideration of the separation of the encapsulations from the mold die. As a result, it is possible to reduce the size of the semiconductor device.